将文件上传到 ASP.NET 中的安全 FTP

Question

我想将文件上传到 FTPS 和 SFTP。我的代码当前使用 FtpWebRequest 对象上传到 FTP。我应该使用哪些更改或类来上传到 FTP、FTPS 和 SFTP 服务器？

Answer 1

SFTP 不是 .NET 的内置协议，您必须使用第三方库，例如 SharpSSH；然而，FTP 和 FTPS 是。有许多商业和开源的第三方库 (适用于 .NET 的 SSH 工厂、适用于 .NET/.NET CF 的 Rebex SFTP、 <一href="http://www.tamirgal.com/blog/page/SharpSSH.aspx" rel="noreferrer">SharpSSH - .NET 的安全外壳 (SSH) 库, 比较 .NET（C#、VB.NET）的 SFTP（SSH 文件传输协议）组件 - SecureBlackbox®）和您需要做一些研究来确定哪一个最适合您的需求。

下面是我编写的一个示例控制台应用程序，它使用 .NET Framework 的 FtpWebRequest 执行 FTP 和 FTPS：

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;
using System.Text;

namespace FtpSslTest
{
    class Program
    {
        static void Main(string[] args)
        {
            string server = null;

            do
            {
                Console.Write("Enter the server to connect to: ");
                server = Console.ReadLine();
            } while (IsServerValid(server) == false);

            UriBuilder ftpUrl = new UriBuilder("ftp", server);

            bool useSsl = GetYesNo("Use SSL?");
            bool allowInvalidCertificate = false;
            if (useSsl)
            {
                allowInvalidCertificate = GetYesNo("Allow invalid SSL certificate?");
            }

            bool useActiveFtp = GetYesNo("Use Active FTP?");

            string path = null;

            do
            {
                Console.Write("Enter the path: ");
                path = Console.ReadLine();
            } while (IsValidPath(path) == false);

            ftpUrl.Path = path;

            Console.Write("Enter the user name: ");
            string userName = Console.ReadLine();

            string password = GetPasswordFromUser();

            Console.WriteLine();
            Console.WriteLine();

            List<string> directoryContents = null;
            try
            {
                directoryContents = DisplayDirectoryContents(ftpUrl.ToString(), userName, password, useSsl, allowInvalidCertificate, useActiveFtp, false);
            }
            catch (WebException ex)
            {
                Console.WriteLine("The request failed with status {0}. {1}", ex.Status, ex.Message);
            }
            catch (Exception ex)
            {
                Console.Error.WriteLine(ex.ToString());
            }

            if (directoryContents != null && directoryContents.Count == 1)
            {
                bool saveFile = GetYesNo(string.Format("Download the file {0} from {1}? ", directoryContents[0], server));

                if (saveFile)
                {
                    string savePath = null;

                    do
                    {
                        Console.Write("Enter a local path to save the file: ");
                        savePath = Console.ReadLine();
                    } while (!IsValidPath(savePath));

                    try
                    {
                        DownloadFileFromServer(ftpUrl.ToString(), userName, password, useSsl, allowInvalidCertificate, useActiveFtp, savePath);
                    }
                    catch (WebException ex)
                    {
                        Console.WriteLine("The request failed with status {0}. {1}", ex.Status, ex.Message);
                    }
                    catch (Exception ex)
                    {
                        Console.Error.WriteLine(ex.ToString());
                    }
                }
            }
        }

        private static bool GetYesNo(string message)
        {
            Console.Write("{0} (Y/N) ", message);

            string input = null;

            do
            {
                input = new string(Console.ReadKey(true).KeyChar, 1);
            } while (!input.Equals("Y", StringComparison.CurrentCultureIgnoreCase) && !input.Equals("N", StringComparison.CurrentCultureIgnoreCase));

            Console.WriteLine(input);

            return input.Equals("Y", StringComparison.CurrentCultureIgnoreCase);
        }

        private static bool IsValidPath(string path)
        {
            bool validPath = false;

            validPath = path != null && path.IndexOfAny(Path.GetInvalidPathChars()) < 0;

            if (validPath == false)
            {
                Console.WriteLine("You must enter a valid path.");
            }

            return validPath;
        }

        private static bool IsServerValid(string server)
        {
            bool serverValid = false;

            if (!string.IsNullOrEmpty(server))
            {
                try
                {
                    IPAddress[] addresses = Dns.GetHostAddresses(server);
                    serverValid = (addresses != null && addresses.Length > 0);
                }
                catch (SocketException ex)
                {
                    Console.WriteLine(ex.Message);
                }
            }
            else
            {
                Console.WriteLine("You must provide a valid host name or IP address.");
            }

            return serverValid;
        }

        private static string GetPasswordFromUser()
        {
            Console.Write("Enter the password: ");
            StringBuilder password = new StringBuilder();

            char readChar = '\x00';
            while (readChar != '\r')
            {
                readChar = Console.ReadKey(true).KeyChar;

                if (readChar == '\b')
                {
                    if (password.Length > 0)
                    {
                        password.Length--;
                        Console.Write("\b \b");
                    }
                }
                else if (readChar != '\r')
                {
                    Console.Write('*');
                    password.Append(readChar);
                }
            }

            return password.ToString();
        }

        public static bool ServicePointManager_ServerCertificateValidationCallback(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
        {
            bool allowCertificate = true;

            if (sslPolicyErrors != SslPolicyErrors.None)
            {
                Console.WriteLine("Accepting the certificate with errors:");
                if ((sslPolicyErrors & SslPolicyErrors.RemoteCertificateNameMismatch) == SslPolicyErrors.RemoteCertificateNameMismatch)
                {
                    Console.WriteLine("\tThe certificate subject {0} does not match.", certificate.Subject);
                }

                if ((sslPolicyErrors & SslPolicyErrors.RemoteCertificateChainErrors) == SslPolicyErrors.RemoteCertificateChainErrors)
                {
                    Console.WriteLine("\tThe certificate chain has the following errors:");
                    foreach (X509ChainStatus chainStatus in chain.ChainStatus)
                    {
                        Console.WriteLine("\t\t{0}", chainStatus.StatusInformation);

                        if (chainStatus.Status == X509ChainStatusFlags.Revoked)
                        {
                            allowCertificate = false;
                        }
                    }
                }

                if ((sslPolicyErrors & SslPolicyErrors.RemoteCertificateNotAvailable) == SslPolicyErrors.RemoteCertificateNotAvailable)
                {
                    Console.WriteLine("No certificate available.");
                    allowCertificate = false;
                }

                Console.WriteLine();
            }

            return allowCertificate;
        }

        private static FtpWebRequest CreateFtpWebRequest(string ftpUrl, string userName, string password, bool useSsl, bool allowInvalidCertificate, bool useActiveFtp)
        {
            FtpWebRequest request = (FtpWebRequest)WebRequest.Create(ftpUrl);
            request.Credentials = new NetworkCredential(userName, password);

            if (useSsl)
            {
                request.EnableSsl = true;

                if (allowInvalidCertificate)
                {
                    ServicePointManager.ServerCertificateValidationCallback = ServicePointManager_ServerCertificateValidationCallback;
                }
                else
                {
                    ServicePointManager.ServerCertificateValidationCallback = null;
                }
            }

            request.UsePassive = !useActiveFtp;

            return request;
        }

        private static List<string> DisplayDirectoryContents(string ftpUrl, string userName, string password, bool useSsl, bool allowInvalidCertificate, bool useActiveFtp, bool detailed)
        {
            List<string> directoryContents = new List<string>();

            FtpWebRequest request = CreateFtpWebRequest(ftpUrl, userName, password, useSsl, allowInvalidCertificate, useActiveFtp);

            if (detailed)
            {
                request.Method = WebRequestMethods.Ftp.ListDirectoryDetails;
            }
            else
            {
                request.Method = WebRequestMethods.Ftp.ListDirectory;
            }

            Stopwatch stopwatch = new Stopwatch();
            long bytesReceived = 0;

            stopwatch.Start();
            using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
            {
                Console.WriteLine(response.BannerMessage);
                Console.WriteLine(response.WelcomeMessage);
                Console.WriteLine(response.StatusDescription);

                using (Stream responseStream = response.GetResponseStream())
                using (StreamReader responseStreamReader = new StreamReader(responseStream))
                {
                    while (!responseStreamReader.EndOfStream)
                    {
                        string directoryEntry = responseStreamReader.ReadLine();
                        Console.WriteLine(directoryEntry);
                        directoryContents.Add(directoryEntry);
                    }
                }

                Console.WriteLine(response.ExitMessage);
            }
            stopwatch.Stop();

            Console.WriteLine();
            Console.WriteLine("{0} bytes received in {1} seconds.", bytesReceived, stopwatch.ElapsedMilliseconds / 1000.0);

            return directoryContents;
        }

        private static List<string> ListDirectoryContents(string ftpUrl, string userName, string password, bool useSsl, bool allowInvalidCertificate, bool useActiveFtp, bool detailed)
        {
            List<string> directoryContents = new List<string>();

            FtpWebRequest request = CreateFtpWebRequest(ftpUrl, userName, password, useSsl, allowInvalidCertificate, useActiveFtp);

            if (detailed)
            {
                request.Method = WebRequestMethods.Ftp.ListDirectoryDetails;
            }
            else
            {
                request.Method = WebRequestMethods.Ftp.ListDirectory;
            }

            using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
            {
                using (Stream responseStream = response.GetResponseStream())
                using (StreamReader responseStreamReader = new StreamReader(responseStream))
                {
                    while (!responseStreamReader.EndOfStream)
                    {
                        string directoryEntry = responseStreamReader.ReadLine();
                        directoryContents.Add(directoryEntry);
                    }
                }

            }

            return directoryContents;
        }

        private static void DownloadFileFromServer(string ftpUrl, string userName, string password, bool useSsl, bool allowInvalidCertificate, bool useActiveFtp, string savePath)
        {
            FtpWebRequest request = CreateFtpWebRequest(ftpUrl, userName, password, useSsl, allowInvalidCertificate, useActiveFtp);

            request.Method = WebRequestMethods.Ftp.DownloadFile;

            Stopwatch stopwatch = new Stopwatch();
            long bytesReceived = 0;

            stopwatch.Start();
            using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
            {
                Console.WriteLine(response.BannerMessage);
                Console.WriteLine(response.WelcomeMessage);
                Console.WriteLine(response.StatusDescription);

                using (Stream responseStream = response.GetResponseStream())
                using (FileStream saveFileStream = File.OpenWrite(savePath))
                {
                    // Note that this method call requires .NET 4.0 or higher. If using an earlier version it will need to be replaced.
                    responseStream.CopyTo(saveFileStream);
                }

                bytesReceived = response.ContentLength;
                Console.WriteLine(response.ExitMessage);
            }
            stopwatch.Stop();

            Console.WriteLine();
            Console.WriteLine("{0} bytes received in {1} seconds.", bytesReceived, stopwatch.ElapsedMilliseconds / 1000.0);
        }

        private static void UploadFileToServer(string ftpUrl, string userName, string password, bool useSsl, bool allowInvalidCertificate, bool useActiveFtp, string filePath)
        {
            FtpWebRequest request = CreateFtpWebRequest(ftpUrl, userName, password, useSsl, allowInvalidCertificate, useActiveFtp);

            request.Method = WebRequestMethods.Ftp.UploadFile;

            Stopwatch stopwatch = new Stopwatch();
            long bytesReceived = 0;

            stopwatch.Start();
            long bytesSent = 0;
            using (Stream requestStream = request.GetRequestStream())
            using (FileStream uploadFileStream = File.OpenRead(filePath))
            {
                // Note that this method call requires .NET 4.0 or higher. If using an earlier version it will need to be replaced.
                uploadFileStream.CopyTo(requestStream);
                bytesSent = uploadFileStream.Position;
            }

            using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
            {
                Console.WriteLine(response.BannerMessage);
                Console.WriteLine(response.WelcomeMessage);
                Console.WriteLine(response.StatusDescription);

                bytesReceived = response.ContentLength;
                Console.WriteLine(response.ExitMessage);
            }
            stopwatch.Stop();

            Console.WriteLine();
            Console.WriteLine("{0} bytes sent in {1} seconds.", bytesSent, stopwatch.ElapsedMilliseconds / 1000.0);
        }
    }
}

您还可以通过在示例应用程序中使用以下配置文件来获取用于调试目的的详细跟踪：

<?xml version="1.0"?>
<configuration>
  <system.diagnostics>
    <sources>
      <source name="System.Net">
        <listeners>
          <add name="TraceFile"/>
        </listeners>
      </source>
      <source name="System.Net.Sockets" maxdatasize="1024">
        <listeners>
          <add name="TraceFile"/>
        </listeners>
      </source>
    </sources>
    <sharedListeners>
      <add name="TraceFile" type="System.Diagnostics.TextWriterTraceListener" initializeData="System.Net.trace.log" traceOutputOptions="DateTime"/>
    </sharedListeners>
    <switches>
      <add name="System.Net" value="Verbose"/>
      <!--<add name="System.Net.Sockets" value="Verbose"/>-->
    </switches>
    <trace autoflush="true" />
  </system.diagnostics>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
  </startup>
</configuration>

Answer 2

我使用这个库通过 sftp 下载和上传文件。如果您下载源代码，应该是如何使用该库的示例。 http://sshnet.codeplex.com